PressCNRS international magazine

Table of contents


Digital Lenses Go Liquid

variopticThere's a substantial revolution afoot in the world of miniaturized optics. For focusing or zooming in and out, it's goodbye to the mechanical components that move the lenses in your camera, and time to welcome their successors: autofocus (AF) and zoom lenses with no moving parts. It took inventor Bruno Berge1 ten years of research and four years of development at Varioptic,2 the company he founded in 2002, for the optical system to become fully operational. How does it work? “Inside a sealed cell, we enclose two immiscible3 liquids that have the same density: One is a conductor, like water, the other a non-conductor, like oil. We then apply an electrical voltage,” explains Berge, Varioptic's scientific director. “The concave interface between the two liquids is very sensitive to the voltage: it changes shape fairly quickly and very reversibly... So the quality of the image depends on the voltage applied.” High optical quality and a very wide optical power range, together with a response time of about 50 milliseconds, are the main advantages of these new lenses. They are also resistant to the harsh treatment (heat or shock) that they may undergo when used on a daily basis in mobile devices such as cell phones, where these lenses have found their first application. The miniature cameras incorporated inside cell phones require high image quality (over 2-3 megapixels) and, like their larger counterparts, must be able to adjust focus and zoom. The problem is that mechanical systems remain costly (the optical system alone makes up half the price of a digital camera), consume a lot of energy, and are difficult to miniaturize while maintaining high image quality. These are all setbacks that don't affect Varioptic's new lens system.
Certified by major manufacturers of cell phones, particularly in Asia, the lenses are now available on the market. Other applications are already being considered, like imaging systems (webcams, observation and surveillance cameras, cars, industrial endoscopes, etc.), lasers, ophthalmology devices, and many more. But as Berge enthusiastically points out, the future holds much promise: “greater simplicity, lower production costs, a wider range of lens sizes–from the very small to the very large depending on the application, there are a multitude of possible technological improvements.”

Alissar Cheaïb

Notes :

1. At the ENS physics laboratory in Lyon (CNRS / École normale supérieure de Lyon/ Université Lyon-I) and the Joseph Fourier University in Grenoble.
3. Which do not mix together.

Contacts :

> Bruno Berge
Laboratoire de physique de l'ENS de Lyon.


Back to homepageContactcredits